Payment Backdated

Hi, just a quick simple question, I understand once awarded pip, they backdate you payment from when you made claim , from going back through my text I can see a text Dated 21 June it reads Thanks for claiming Personal Independence Payment. We will shortly send you a 'How your disability affects you' form. You'll need to fill it in carefully and return it to us so we can see if we can award you PIP. Is That the date you go from or after the form is returned? Many Thanks in advance.